plasma fault at start up

[dv8i]

Hi with reference to my last post i purchased a new tip and electrode for my plasma but to my dismay its still playing up. its a murex saber cut 40i and on switching the unit on all seems fine, when i attempt to cut, the air preflow starts but after 4 seconds the overload light comes on with no attempt to cut or sign of spark and on releasing the button the air flow continues for 5 or 6 seconds. the hand book says that when the button on the torch is depressed the air should flow for 2 seconds and then the hf should start to initiate the cut and then the postflow continues as it should,but alas no cutting is achieved. has anyone any idea what the problem is? any help would be greatly appreciated
cheers gary

 

[weldequip]

What's your air pressure set at?
weldequip

 

[dv8i]

thanks for your reply, the air presure is set at 65psi
cheers gary

 

[weldequip]

Too high. I think it say's in the manual as high as 75psi? which is actually a misprint! Try it at around 45-50psi & see how you go
weldequip

 

[dv8i]

thanks i'll try that and see how it goes
cheers gary

 

[dv8i]

Hi i tried adjusting the pressure to 45psi and also tried higher and lower pressures but still no spark, is there anything else that i could try? i checked the continuity of the main lead to the torch and also the earth/work return lead and also the operation of the lead from the button all seem fine. it appears as if the sequence is interupted somewhere, on pressing the torch button the sequence starts as it should energising the airflow but after the 2 second timer the high frequency, the inverter or the cutting arc (current) come on, the overload light comes on. any help is greatly appreciated
regards gary

 

[weldequip]

Reckon it's a machine fault then Try Murex service on www.murexwelding.co.uk
weldequip

 

[Jake SS]

If you have checked all the simple things then yes does not sound good. May be the power board, signaling a fault.

 

[dv8i]

thanks for your help guys, looks like im going to have to bite the bullet and spend some money and at least get some investigation done.
thanks for your help
best regards gary

 

[s00073055]

sabre arc

hello i now have the same problem that you have with the sabre arc 40i was wondering if ever got to the root of the problem many thanks

 

[marks]

hi on these machine's there are 4 diode's under the main pcb at rear they allways go open circuit or short check these first..